Documentation
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Overview ¶
Package token defines constants representing the lexical tokens of the Go programming language and basic operations on tokens (printing, predicates).
Index ¶
- Constants
- Variables
- type File
- func (f *File) AddLine(offset int)
- func (f *File) AddLineInfo(offset int, filename string, line int)
- func (f *File) Base() int
- func (f *File) Line(p Pos) int
- func (f *File) LineCount() int
- func (f *File) MergeLine(line int)
- func (f *File) Name() string
- func (f *File) Offset(p Pos) int
- func (f *File) Pos(offset int, rel RelPos) Pos
- func (f *File) Position(p Pos) (pos Position)
- func (f *File) PositionFor(p Pos, adjusted bool) (pos Position)
- func (f *File) SetLines(lines []int) bool
- func (f *File) SetLinesForContent(content []byte)
- func (f *File) Size() int
- type Pos
- func (p Pos) Add(n int) Pos
- func (p Pos) Before(q Pos) bool
- func (p Pos) Column() int
- func (p Pos) File() *File
- func (p Pos) Filename() string
- func (p Pos) HasRelPos() bool
- func (p Pos) IsNewline() bool
- func (p Pos) IsValid() bool
- func (p Pos) Line() int
- func (p Pos) Offset() int
- func (p Pos) Position() Position
- func (p Pos) RelPos() RelPos
- func (p Pos) String() string
- func (p Pos) WithRel(rel RelPos) Pos
- type Position
- type RelPos
- type Token
Constants ¶
const ( LowestPrec = lowestPrec UnaryPrec = unaryPrec HighestPrec = highestPrec )
A set of constants for precedence-based expression parsing. Non-operators have lowest precedence, followed by operators starting with precedence 1 up to unary operators. The highest precedence serves as "catch-all" precedence for selector, indexing, and other operator and delimiter tokens.
Variables ¶
var NoPos = Pos{}
NoPos is the zero value for Pos; there is no file and line information associated with it, and NoPos().IsValid() is false. NoPos is always smaller than any other Pos value. The corresponding Position value for NoPos is the zero value for Position.
Functions ¶
This section is empty.
Types ¶
type File ¶
type File struct {
// contains filtered or unexported fields
}
A File has a name, size, and line offset table.
func (*File) AddLine ¶
AddLine adds the line offset for a new line. The line offset must be larger than the offset for the previous line and smaller than the file size; otherwise the line offset is ignored.
func (*File) AddLineInfo ¶
AddLineInfo adds alternative file and line number information for a given file offset. The offset must be larger than the offset for the previously added alternative line info and smaller than the file size; otherwise the information is ignored.
AddLineInfo is typically used to register alternative position information for //line filename:line comments in source files.
func (*File) Line ¶
Line returns the line number for the given file position p; p must be a Pos value in that file or NoPos.
func (*File) MergeLine ¶
MergeLine merges a line with the following line. It is akin to replacing the newline character at the end of the line with a space (to not change the remaining offsets). To obtain the line number, consult e.g. Position.Line. MergeLine will panic if given an invalid line number.
func (*File) Offset ¶
Offset returns the offset for the given file position p; p must be a valid Pos value in that file. f.Offset(f.Pos(offset)) == offset.
func (*File) Pos ¶
Pos returns the Pos value for the given file offset; the offset must be <= f.Size(). f.Pos(f.Offset(p)) == p.
func (*File) Position ¶
Position returns the Position value for the given file position p. Calling f.Position(p) is equivalent to calling f.PositionFor(p, true).
func (*File) PositionFor ¶
PositionFor returns the Position value for the given file position p. If adjusted is set, the position may be adjusted by position-altering //line comments; otherwise those comments are ignored. p must be a Pos value in f or NoPos.
func (*File) SetLines ¶
SetLines sets the line offsets for a file and reports whether it succeeded. The line offsets are the offsets of the first character of each line; for instance for the content "ab\nc\n" the line offsets are {0, 3}. An empty file has an empty line offset table. Each line offset must be larger than the offset for the previous line and smaller than the file size; otherwise SetLines fails and returns false. Callers must not mutate the provided slice after SetLines returns.
func (*File) SetLinesForContent ¶
SetLinesForContent sets the line offsets for the given file content. It ignores position-altering //line comments.
type Pos ¶
type Pos struct {
// contains filtered or unexported fields
}
Pos is a compact encoding of a source position within a file, as well as relative positioning information. It can be converted into a Position for a more convenient, but much larger, representation.
func (Pos) File ¶
File returns the file that contains the position p or nil if there is no such file (for instance for p == NoPos).
type Position ¶
type Position struct {
Filename string // filename, if any
Offset int // offset, starting at 0
Line int // line number, starting at 1
Column int // column number, starting at 1 (byte count)
}
Position describes an arbitrary source position including the file, line, and column location. A Position is valid if the line number is > 0.
type RelPos ¶
type RelPos int
RelPos indicates the relative position of token to the previous token.
const ( // NoRelPos indicates no relative position is specified. NoRelPos RelPos = iota // Elided indicates that the token for which this position is defined is // not rendered at all. Elided // NoSpace indicates there is no whitespace after this token. NoSpace // Blank means there is horizontal space after this token. Blank // Newline means there is a single newline after this token. Newline // NewSection means there are two or more newlines after this token. NewSection )
type Token ¶
type Token int
Token is the set of lexical tokens of the CUE configuration language.
const ( // Special tokens ILLEGAL Token = iota EOF COMMENT ATTRIBUTE // @foo(bar,baz=4) // Identifiers and basic type literals // (these tokens stand for classes of literals) IDENT // main, _tmp INT // 12_345Mi, 0700, 0xdeadbeef, 1.2M FLOAT // 123.45, // DURATION // 3m4s TODO STRING // "abc" INTERPOLATION // a part of a template string, e.g. `"age: \(` BOTTOM // _|_ // Operators and delimiters ADD // + SUB // - MUL // * POW // ^ QUO // / REM // % IQUO // quo IREM // rem IDIV // div IMOD // mod AND // & OR // | LAND // && LOR // || BIND // = EQL // == LSS // < GTR // > NOT // ! ARROW // <- NEQ // != LEQ // <= GEQ // >= MAT // =~ NMAT // !~ LPAREN // ( LBRACK // [ LBRACE // { COMMA // , PERIOD // . ELLIPSIS // ... RPAREN // ) RBRACK // ] RBRACE // } SEMICOLON // ; COLON // : OPTION // ? IF FOR IN LET TRUE FALSE NULL )
The list of tokens.
func (Token) IsKeyword ¶
IsKeyword returns true for tokens corresponding to keywords; it returns false otherwise.
func (Token) IsLiteral ¶
IsLiteral returns true for tokens corresponding to identifiers and basic type literals; it returns false otherwise.
func (Token) IsOperator ¶
IsOperator returns true for tokens corresponding to operators and delimiters; it returns false otherwise.
func (Token) Precedence ¶
Precedence returns the operator precedence of the binary operator op. If op is not a binary operator, the result is LowestPrecedence.
func (Token) String ¶
String returns the string corresponding to the token tok. For operators, delimiters, and keywords the string is the actual token character sequence (e.g., for the token ADD, the string is "+"). For all other tokens the string corresponds to the token constant name (e.g. for the token IDENT, the string is "IDENT").
Source Files